Cation exchange synthesis and optoelectronic properties of type II CdTe–Cu2−xTe nano-heterostructures

Kriegel, Ilka; Wisnet, Andreas; Kandada, Ajay Ram Srimath; Scotognella, Francesco; Tassone, F.; Scheu, Christina; Zhang, Hui; Govorov, Alexander O.; Rodrı́guez-Fernández, Jessica; Feldmann, Jochen

doi:10.1039/c3tc32049a

Cited by 30 publications

(27 citation statements)

References 97 publications

(167 reference statements)

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“…Since the wurtzite CdS and orthorhombic Cu 2 S share similar anion sublattice, the lattice volume only decreases by 8% when CdS was converted to Cu 2 S, and therefore, the morphology and size of nanorods were well preserved after the cation exchange. Similar structures have been obtained in CdTe/Cu 2-x Te 44 and CdSe/ PbSe [99] systems.…”

Section: D Linear Heterostructuressupporting

confidence: 83%

Wet-Chemical Synthesis and Applications of Semiconductor Nanomaterial-Based Epitaxial Heterostructures

Chen

et al. 2019

Nano-Micro Lett.

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HIGHLIGHTS• The synthesis of semiconductor nanomaterial-based epitaxial heterostructures by wet-chemical methods is introduced. Various architectures based on different kinds of seeds or templates are illustrated, and their growth mechanisms are discussed in detail.• The applications of epitaxial heterostructures in optoelectronics, thermoelectrics, and catalysis are discussed. ABSTRACTSemiconductor nanomaterial-based epitaxial heterostructures with precisely controlled compositions and morphologies are of great importance for various applications in optoelectronics, thermoelectrics, and catalysis. Until now, various kinds of epitaxial heterostructures have been constructed. In this minireview, we will first introduce the synthesis of semiconductor nanomaterial-based epitaxial heterostructures by wet-chemical methods. Various architectures based on different kinds of seeds or templates are illustrated, and their growth mechanisms are discussed in detail. Then, the applications of epitaxial heterostructures in optoelectronics, catalysis, and thermoelectrics are described. Finally, we provide some challenges and personal perspectives for the future research directions of semiconductor nanomaterial-based epitaxial heterostructures. C ata lys is L i g h te m it ti ng dev ic e P h o t o v ol taic de v ic e T h e r m al elect ic d e v i c e Semiconductor Epitaxial Heterostructuressolution containing Cd-oleate [33]. The thermal decomposition of (NH 4 ) 2 MoS 4 or (NH 4 ) 2 WS 4 not only provided the sulfur source for the nucleation and growth of CdS seeds, but also acted as the precursor which decomposed to form MoS 2 or WS 2 nanosheets (NSs). Hydro-/Solvothermal StrategyEpitaxial heterostructures can also be prepared by the hydro-/solvothermal strategy, a typical wet-chemical synthesis method, which uses water or organic solvents as the reaction medium in a sealed steel pressure reactor with Teflon liner. The chemical reaction can proceed at the temperature higher than the boiling point of the solvent. Under such condition, high pressure can be generated, promoting the reaction and improving the crystallinity of the synthesized NCs [34]. The main advantage of the hydro-/solvothermal strategy is that almost all precursors can dissolve in the solvent at high pressure and temperature. Besides that, the merits of hydro-/solvothermal strategy, including the easy operability, high yield, and low cost, make it an attractive choice for constructing epitaxial heterostructures. As a typical example, Wang et al. reported the epitaxial growth of α-Fe 2 O 3 on CdS nanowires (NWs) via a two-step solvothermal process using N,N-dimethylformamide as solvent and poly(vinylpyrrolidone) as surfactant [35].Even though hydro-/solvothermal strategy has been widely used to prepare epitaxial heterostructures, it has disadvantages as well. Firstly, it is impossible to observe the reaction process in situ since the reaction occurs in a sealed autoclave, making it difficult to propose the growth mechanism. Besides, since the hydro-/solvothermal r...

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Section: D Linear Heterostructuressupporting

confidence: 83%

Wet-Chemical Synthesis and Applications of Semiconductor Nanomaterial-Based Epitaxial Heterostructures

Chen

et al. 2019

Nano-Micro Lett.

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“…17,18,33 The Drude dielectric constant  Drude (, as a function of the frequency , has the form: Several recent papers have shown that the Drude model provides a reliable description of semiconductor nanocrystals with mobile carriers.…”

Section: Microwave-assisted Synthesis and Characterization Of Covellimentioning

confidence: 99%

Covellite CuS nanocrystals: realizing rapid microwave-assisted synthesis in air and unravelling the disappearance of their plasmon resonance after coupling with carbon nanotubes

et al. 2016

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Semiconductor nanocrystals that show plasmonic resonance represent an emerging class of highly promising plasmonic materials with potential applications in diverse fields, such as sensing and optical and optoelectronic devices. We report a new approach to synthesizing homogeneous covellite CuS nanoplatelets in air and the almost complete disappearance of their plasmonic resonance once coupled with multiwalled carbon nanotubes (MWCNTs). These nanoplatelets were rapidly synthesized by a simple microwave-assisted approach at a relatively low reaction temperature in air, instead of under N2 as reported previously. These less severe synthesis conditions were enabled by appropriately selecting a Cu precursor and preparing a precursor sulfur solution (instead of using solid sulfur) and by using microwave radiation as the heat source. The advantages of utilizing microwave irradiation, including uniform and rapid heating, became clear after comparing the results of the synthesis with those achieved using a conventional oil-bath method under N2. The CuS nanoplatelets prepared in this way showed very strong plasmon resonance at c. 1160 nm as a result of their free charge carriers at the calculated density of nh = 1.5 × 10(22) cm(-3) based on the Drude model. With the aim of exploring their potential for near-infrared responsive optoelectronic devices, they were hybridized with functionalized MWCNTs. Their strong plasmon resonance almost completely disappeared on hybridization. Detailed investigations excluded the effect of possible structural changes in the CuS nanoplatelets during the hybridization process and a possible effect on the plasmon resonance arising from the chemical bonding of surface ligands. Charge transfer was considered to be the main reason for the almost complete disappearance of the plasmon resonance, which was further confirmed by terahertz (THz) time-domain spectrometry and THz time-resolved spectrometry measurements performed on the CuS-MWCNT nanohybrids. By extracting the rising and relaxation constants through fitting a single-exponential rising function and a bi-exponential relaxation function, in combination with the results of THz differential transmission as a function of the NIR pump fluence, it was found that hole injection changed the electronic properties of the MWCNTs only subtly on a short picosecond time scale, whereas the nature of the band structure of the MWCNTs remained largely unchanged. These findings aid our understanding of recently emerging semiconductor plasmonics and will also help in developing practical applications.

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“…2 Nanoscale cation exchange provides control over the spatial arrangement of different phases within nanocrystals, allowing for the synthesis of heterostructures with tunable properties. [26][27][28] Cation exchange therefore can be an important tool for controlling the plasmonic properties of semiconductor nanocrystals that combines the spatial resolution of top-down fabrication techniques with the high throughput of solution-based syntheses. The use of cation exchange to modify the optical properties of metal chalcogenides nanocrystals remains a novel field of inquiry.…”

Section: Introductionmentioning

confidence: 99%

Analytical modeling of localized surface plasmon resonance in heterostructure copper sulfide nanocrystals

Caldwell

Ding

et al. 2014

The Journal of Chemical Physics

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Localized surface plasmon resonance (LSPR) in semiconductor nanocrystals is a relatively new field of investigation that promises greater tunability of plasmonic properties compared to metal nanoparticles. A novel process by which the LSPR in semiconductor nanocrystals can be altered is through heterostructure formation arising from solution-based cation exchange. Herein, we describe the development of an analytical model of LSPR in heterostructure copper sulfide-zinc sulfide nanocrystals synthesized via a cation exchange reaction between copper sulfide (Cu(1.81)S) nanocrystals and Zn ions. The cation exchange reaction produces dual-interface, heterostructure nanocrystals in which the geometry of the copper sulfide phase can be tuned from a sphere to a thin disk separating symmetrically-grown sulfide (ZnS) grains. Drude model electronic conduction and Mie-Gans theory are applied to describe how the LSPR wavelength changes during cation exchange, taking into account the morphology evolution and changes to the local permittivity. The results of the modeling indicate that the presence of the ZnS grains has a significant effect on the out-of-plane LSPR mode. By comparing the results of the model to previous studies on solid-solid phase transformations of copper sulfide in these nanocrystals during cation exchange, we show that the carrier concentration is independent of the copper vacancy concentration dictated by its atomic phase. The evolution of the effective carrier concentration calculated from the model suggests that the out-of-plane resonance mode is dominant. The classical model was compared to a simplified quantum mechanical model which suggested that quantum mechanical effects become significant when the characteristic size is less than ~8 nm. Overall, we find that the analytical models are not accurate for these heterostructured semiconductor nanocrystals, indicating the need for new model development for this emerging field.

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Cation exchange synthesis and optoelectronic properties of type II CdTe–Cu2−xTe nano-heterostructures

Cited by 30 publications

References 97 publications

Wet-Chemical Synthesis and Applications of Semiconductor Nanomaterial-Based Epitaxial Heterostructures

Wet-Chemical Synthesis and Applications of Semiconductor Nanomaterial-Based Epitaxial Heterostructures

Covellite CuS nanocrystals: realizing rapid microwave-assisted synthesis in air and unravelling the disappearance of their plasmon resonance after coupling with carbon nanotubes

Analytical modeling of localized surface plasmon resonance in heterostructure copper sulfide nanocrystals

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